The luminous Audra McDonald is probably nobody's idea of a plain-Jane spinster, and even less likely to pass for one when she opens her mouth to release that full-bodied soprano.

The luminous Audra McDonald is probably nobody’s idea of a plain-Jane spinster, and even less likely to pass for one when she opens her mouth to release that full-bodied soprano. So it’s a testament to her gifts that McDonald’s vibrant characterization in such a role — as spirited, smart and affecting as her luxuriant vocals — gives “110 in the Shade” a touching verismo in the midst of Santo Loquasto’s stylized design. Ambling along for much of the time like a low-rent “Oklahoma,” this 1963 musical version of “The Rainmaker” gets by on its charming score, old-fashioned romantic heart and, most of all, its magnetic lead, but the temperature rarely rises above that of a mild spring day.

Faithfully adapted by N. Richard Nash from his 1954 play (filmed by Paramount with Burt Lancaster and Katharine Hepburn), the show is a fondly regarded midlevel entry in the American musical theater canon whose fame couldn’t match that of composing team Tom Jones and Harvey Schmidt’s earlier and somewhat more precious Off Broadway hit, “The Fantasticks.”

While “110” also was overshadowed by “Funny Girl” and “Hello, Dolly,” two far showier leading-lady vehicles that premiered the same season, the tuner is nonetheless a sturdy showcase for a talented female star. As such, the revival represents a tidy segue for Roundabout from its recent “The Apple Tree,” which existed solely for Kristin Chenoweth the same way this production is built around the versatile McDonald, whose last Broadway musical role was in 1999’s “Marie Christine.”

Loquasto’s striking design — dominated by a massive overhanging disc that all but fills the Studio 54 stage and serves as both the sun and the moon, washed by the countless color variations of Christopher Akerlind’s warm lighting — might give the initial impression that a more inventive sensibility were being brought to the rustic romance. But Lonny Price’s fairly pedestrian production serves up the material largely as is, despite the innovation of color-blind casting in a show set in the Depression-era Texas Panhandle.

There’s also a slight shift in character focus to explain the failure of ranch girl Lizzie Curry (McDonald) to land a husband, playing down her supposed homeliness and instead emphasizing her feisty, outspoken intelligence.

However, Lizzie is no shrew waiting to be tamed. She desperately yearns to be married, which McDonald conveys with aching vulnerability in the song “Love Don’t Turn Away.” Her sweet-natured, widowed father, H.C. (John Cullum), and doting brothers, Noah (Chris Butler) and Jimmy (Bobby Steggert), are equally anxious to see her hitched and happy. Prime target for their matchmaking endeavors is town sheriff File (Christopher Innvar), a brooding loner burned by love when his wife walked out on him.

A more unexpected candidate emerges when wandering conman Starbuck (Steve Kazee) breezes into town, promising to quench Lizzie’s parched heart and end the drought gripping the community by miraculously producing rain for a $100 fee.

Particularly in the first act, Price could lean harder on the accelerator, but the director makes good use of the stage’s central revolve to keep things in motion. This is not the most dynamic of stories, its romantic triangle seeming to form only minutes before Lizzie makes her choice, but the appeal of Nash’s book and of Jones and Schmidt’s correspondingly mellow songs is the gentle, low-key way they express real feelings.

Lizzie’s need for emotional fulfillment, Starbuck’s advocacy of the limitless power of dreaming and File’s self-imprisoning heartache all are sweetly rendered in a show that grows more engaging after a plodding start. And as much as it could seem a positive-thinking cliche, Starbuck’s mission to teach Lizzie to see herself as beautiful has the air of an understated fairy tale unfolding under an enchanted starry sky — “Everything beautiful happens at night,” sing Lizzie and the townsfolk.

The musical is laced with well crafted songs that enhance and advance the narrative, the best of them entrusted to a most capable musical storyteller in McDonald. She vamps playfully through “Raunchy,” imagining herself the kind of flirtatious woman who has no trouble attracting men; sings wistfully of her unadorned desires in “Simple Little Things”; exchanges tentative overtures of love with Innvar’s File in “A Man and a Woman”; angrily exposes her fear while cranking up her soprano into full dramatic throttle in “Old Maid”; and all but explodes with the girlish joy of self-discovery and unleashed emotion in “Is It Really Me?”

Music director Paul Gemignani and orchestrator Jonathan Tunick compensate for the reduced ranks of musicians and cast (the town’s July Fourth picnic looks distinctly underpopulated) by highlighting the score’s lightness and airiness.

Ensemble songs “Another Hot Day” and its corresponding “The Rain Song” provide the elemental echo for the story’s romantic longing. Comedy numbers “You’re Not Fooling Me” and “Poker Polka” are hokey and disposable. but “Little Red Hat” is a frisky delight, performed with brio by the winning Steggert and Carla Duren as Jimmy’s flighty girlfriend Snookie. The song is also one of the rare occasions when choreographer Dan Knechtges’ work is allowed to develop.

In addition to Steggert, the supporting cast has an asset in the dependable Cullum, who makes a steadfast, nurturing figure of Lizzie’s father. Tall, lean and handsome in a throwback ’50s mold, Innvar has a nice unassuming stage presence that befits a character who shrinks from public declarations for most of the action.

While his vocals are pleasing, Kazee is a less ideal match for seductive dreamweaver Starbuck. In fairness, the fault may lie not so much with the actor as with whoever decided to give him sleazy villain hair and outfit him (Loquasto also did the otherwise efficient costumes) like a Castro cowboy in soccer mom jeans. He also gets stuck with the dud song “Melisande,” its cloying whimsy representative of the less durable aspects of Jones and Schmidt’s work.

But even with two leading men competing for her attention and ours, this is McDonald’s show all the way, and she shines.

110 in the Shade

Studio 54; 997 seats; $111.25 top

Production

A Roundabout Theater Company presentation of a musical in two acts with music by Harvey Schmidt, lyrics by Tom Jones, book by N. Richard Nash, based on his play "The Rainmaker." Directed by Lonny Price. Music direction, Paul Gemignani. Choreography, Dan Knechtges.